The subject matter disclosed herein relates to compressors. More specifically, the subject disclosure relates to fluid flow in a compressor.
Compressors are utilized in many different applications, for example, in vapor cycle refrigeration systems. In a typical vapor cycle refrigeration system, a circulating refrigerant flows through four components: a compressor, a condenser, an expansion valve and an evaporator. The refrigerant, in a vapor state, is compressed and heated in the compressor, then is condensed into a liquid in the condenser by a heat sink. The liquid refrigerant then undergoes a rapid reduction in pressure when routed through the expansion valve. The rapid expansion causes an evaporation of at least a portion of the refrigerant resulting in a lowering of the temperature of the refrigerant. The liquid portion of the refrigerant is then evaporated in the evaporator and heat is absorbed from a fluid, typically air for example, flowing thru the evaporator. Compressor power is typically provided by an electric motor.
The compressor portion, powered by an electrical motor, typically includes one or more compressor impellers rotatably located about a rotor shaft in a compressor housing assembly. The refrigerant passes through the impellers in succession, increasing the pressure and the temperature of the refrigerant. In many compressors, impellers are located at opposing ends of the compressor to improve rotor dynamics conditions. To convey the refrigerant between the impellers, one or more conduits are provided external to the housing assembly and connected at one or more ports. The refrigerant passes through a first impeller and exits the housing through the one or more ports into a first end of the one or more conduits and reenters the housing via ports near a second impeller and passes through the second impeller. In some systems, during the flow along the one or more conduits, the refrigerant is passed through a heat exchanger to remove heat generated from the compression via the first impeller. Additionally, a motor stator portion is located between the first and second impeller and is subjected to the heat due to the inefficiency in converting electric power to mechanical power. To cool the stator, cooling jackets are often added around the exterior of the stator portion.
The porting and connections to external conduits introduce additional components to the system and add weight. Further, the connections introduce a potential source of leakage which negatively impacts the performance and efficiency of the compressor and the refrigeration system.